General scaling limitations of ground-plane and isolated-object cloaks

TL;DR

This paper demonstrates fundamental physical limitations on the scalability of transformation-based cloaks for ground-plane and isolated objects, highlighting that cloak thickness and imperfections scale with object size.

Contribution

It provides a theoretical proof of size-dependent constraints on the physical parameters of cloaks, revealing inherent limitations in their practical implementation.

Findings

Cloak thickness must scale with object size.

Absorption and imperfections inversely scale with object thickness.

Bounded refractive indices impose a lower bound on effective cross-section.

Abstract

We prove that, for arbitrary three-dimensional transformation-based invisibility cloaking of an object above a ground plane or of isolated object, there are practical constraints that increase with the object size. In particular, we show that the cloak thickness must scale proportional to the thickness of the object being cloaked, assuming bounded refractive indices, and that absorption discrepancies and other imperfections must scale inversely with the object thickness. For isolated objects, we also show that bounded refractive indices imply a lower bound on the effective cross-section.